/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package DocUpload;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import static java.lang.System.out;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 *
 * @author Mukesh
 */
public class FileDownload extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        try {
            String fileName = request.getParameter("fileName");
            if (fileName == null || fileName.equals("")) {
                throw new ServletException("File Is empty");
            }
            File file = new File(request.getServletContext().getAttribute("FILES_DIR") + File.separator + fileName);
            if (!file.exists()) {
                throw new ServletException("File doesn't exists on server.");
            }
            System.out.println("File location on server::" + file.getAbsolutePath());
            ServletContext ctx = getServletContext();
            InputStream fis = new FileInputStream(file);
            String mimeType = ctx.getMimeType(file.getAbsolutePath());
            response.setContentType(mimeType != null ? mimeType : "application/octet-stream");
            response.setContentLength((int) file.length());
            response.setHeader("Content-Disposition", "attachment; filename=\"" + fileName + "\"");

            ServletOutputStream os = response.getOutputStream();
            byte[] bufferData = new byte[1024];
            int read = 0;
            while ((read = fis.read(bufferData)) != -1) {
                os.write(bufferData, 0, read);
            }
            os.flush();
            os.close();
            fis.close();
            System.out.println("File downloaded at client successfully");

        } finally {
           out.close();
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}
